1. Field of the Invention
The invention relates to a method for controlling and surveying the operation of an elevator system. In addition, an antifriction bearing for use in the method is also the subject matter of the present invention.
2. Description of the Prior Art
The control of an elevator system must meet two demands. On one hand, a control of the operation must occur in correspondence with the signals inputted by the users, wherein also special motion programs can be made use of, on the other hand safety of operation must be surveyed continually, this primarily including surveillance of closing condition of the doors, surveillance of speed of movement and protection against overload.
Such a control and surveillance presupposes the detection and processing of certain input values which have to be continually detected during operation. This usually is done using controls and checking circuitry permitting detection of operating data depending on time and path and evaluation thereof. Therein it is the essential point that the elevator cage is detected in its position and/or movement, respectively, in the elevator shaft as exactly as possible and to bring it to a standstill in a given position.
Detection of the position and/or movement condition, respectively, generally is effected by mechanical arrangements, like tracer systems or belts, ropes or the like directly connected to the elevator cage, by which a direct checking function can be executed. Due to the mechanical construction, however, the possibility of using such systems in case of high moving speeds and large lift heights is limited.
In addition, also meters of different construction are known, which generate pulses or analogue voltages from a rotational movement using frictional engagement, belt drive, chain drive or other kinds of transmission, which values serve as input values for the control. Mostly, it Is a matter of add-on devices with attachments which mostly are subject to a certain amount of slippage and thus e.g. do not permit direct final switch-off in a holding position. Thereby, further switch-off and/or changing circuitry or doubling of the comparatively expensive systems become necessary.